全文获取类型
收费全文 | 1754篇 |
免费 | 19篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 6篇 |
化学工业 | 83篇 |
金属工艺 | 12篇 |
机械仪表 | 21篇 |
建筑科学 | 14篇 |
矿业工程 | 1篇 |
能源动力 | 20篇 |
轻工业 | 75篇 |
水利工程 | 2篇 |
石油天然气 | 2篇 |
无线电 | 55篇 |
一般工业技术 | 98篇 |
冶金工业 | 1316篇 |
原子能技术 | 2篇 |
自动化技术 | 67篇 |
出版年
2023年 | 6篇 |
2022年 | 7篇 |
2021年 | 11篇 |
2020年 | 13篇 |
2019年 | 6篇 |
2018年 | 10篇 |
2017年 | 6篇 |
2016年 | 16篇 |
2015年 | 8篇 |
2014年 | 15篇 |
2013年 | 46篇 |
2012年 | 22篇 |
2011年 | 27篇 |
2010年 | 18篇 |
2009年 | 16篇 |
2008年 | 26篇 |
2007年 | 13篇 |
2006年 | 15篇 |
2005年 | 12篇 |
2004年 | 11篇 |
2003年 | 15篇 |
2002年 | 7篇 |
2001年 | 10篇 |
2000年 | 8篇 |
1999年 | 41篇 |
1998年 | 413篇 |
1997年 | 199篇 |
1996年 | 159篇 |
1995年 | 83篇 |
1994年 | 61篇 |
1993年 | 85篇 |
1992年 | 13篇 |
1991年 | 23篇 |
1990年 | 14篇 |
1989年 | 14篇 |
1988年 | 25篇 |
1987年 | 12篇 |
1986年 | 16篇 |
1985年 | 22篇 |
1984年 | 6篇 |
1983年 | 8篇 |
1982年 | 8篇 |
1981年 | 8篇 |
1980年 | 15篇 |
1979年 | 9篇 |
1978年 | 9篇 |
1977年 | 51篇 |
1976年 | 113篇 |
1975年 | 4篇 |
1971年 | 4篇 |
排序方式: 共有1774条查询结果,搜索用时 0 毫秒
61.
Reversal of pretreatment hypotension and control of hemorrhage in trauma patients by a simple device
JM Civetta ST Nussenfeld EL Nagel BH Kaplan TR Rowe F Pettijohn 《Canadian Metallurgical Quarterly》1977,43(1):20-29
The injection of a suspension of Walker 256 carcinoma cells into the carotid artery of rats produced a model of hematogenously spread cerebral metastases. Most animals died from massive extracerebral tumors of the head and jaw; brain tumors were present in only one-quarter. External carotid artery ligation prior to tumor inoculation did not increase the incidence of fatal brain tumor. When cyclophosphamide, 15 mg/kg, was injected as a single dose on the fourteenth day after tumor inoculation, most of the extracerebral tumor disappeared. Fifty percent of the animals so treated were cured of tumor, but 90% of the remainder died of large intracerebral tumors. Severe cytopathic changes resulting from cyclophosphamide were present in extracerebral or choroid plexus tumors but were mild or nonexistent in intracerebral tumors. These selective effects of cyclophosphamide suggest that water-soluble agents are less effective against tumor in the brain than against extracerebral tumors despite the fact that metastatic tumor breaks down the blood-brain barrier. 相似文献
62.
Besides a thermolabile inhibitor of tissue thromboplastin a thermostable inhibitor was found in human blood serum; molecular weight of the inhibitor (estimated by gel filtration) is 210000-235000 daltons, while molecular weight of a thermolabile inhibitor--480000 daltons. Inhibition of the thrombin formation system by the termostable inhibitor was reversible and was characterized kinetically as a mixed type of inhibition. Both inhibitors were found in blood of rats. Their content varied irrespectively of the state of hemocoagulation. Content of the thermostable inhibitor was distinctly decreased in blood serum after the blockade of reticuloendothelial system by administration of tripane blue. 相似文献
63.
1. Carnitine esters of erucic acid (22:1 n-9 cis), cetoleic acid (22:1 n-11 cis), brassidic acid (22:1 n-9 trans), gadoleic acid (20:1 n-9 cis) and oleic acid (18:1 n-9 cis) have been compared as mitochondrial substrates and as inhibitors of palmitoylcarnitine oxidation in heart and liver mitochondria. 2. Both the rate of intramitochondrial-CoA acylation and the rate of beta-oxidation decreases as the chain length increases from C18 to C22. There are no significant differences among the three C22 isomers as oxidizable substrates. 3. All the tested acylcarnitines inhibit palmitoylcarnitine oxidation. The C18 and C20 acylcarnitines inhibit by virtue of being competing substrates; i.e. the respiration is not inhibited. The C22-isomers inhibit also respiration; this shows that the inhibition of palmitolycarnitine oxidation is not compensated for by oxidation of C22-acylcarnitines. Brassidoylcarnitine inhibits the oxidation of palmitoylcarnitine and respiration less than erucoyl-and cetoleoylcarnitine. The different behaviour of the C22-isomers is probably due to the difference in their competitive properties with respect to long-chain acyl-CoA dehydrogenase. 4. All C22 acylcarnitines seem to be relatively better oxidized in the liver than in the heart mitochondria while their inhibitory effect on the usage of the radioactive palmitoylcarnitine is very similar. 5. Palmitoylcarnitine inhibits almost completely the "endogenous" formation of acetyl-CoA presumably from malate via pyruvate in the liver mitochondria while the C22-acylcarnitines cause only a partial inhibiton of this acetyl-CaO formation. 相似文献
64.
Refusal to eat by the elderly, and subsequent malnutrition, occurs in both institutional and community settings. Causes include physiologic changes associated with aging, mental disorders such as dementia and depression, and medical, social, and environmental factors. Treatment approaches call for management of these causes while considering the roles that medicine, ethics, and culture play in the process. 相似文献
65.
66.
67.
Malignant melanoma of the mucous membranes is rare and has a very poor prognosis. When localized in the nose, the tumor becomes apparent late in the course of the disease with nasal obstruction and epistaxis. Distant metastases are uncommon, but any organ of the body can be involved. A case of a malignant melanoma of the nasal mucosa with metastasis to the small intestine is presented, and the natural history of the metastatic disease is discussed. 相似文献
68.
High pressure vapour-liquid equilibrium data for the CH4Ar, CH4CO, and ArCO systems are presented in this work. The data are obtained isothermally and for each data point T, P, xi, and yi are measured. When possible, the measurements are compared to other published data, and good agreement is found with previous investigations.Each isotherm is subjected to a thermodynamic analysis, and activity coefficients are calculated. When both components are condensable, the ordinary symmetrical convention for normalization of activity coefficients is used, and when one component is supercritical, the unsymmetrical convention is used.The activity coefficients are adjusted to a constant pressure via the Poynting correction factor, and these pressure adjusted activity coefficients are subjected to a thermodynamic consistency test based on the isothermal-isobasic form of the Gibbs-Duhem equation. It is found that the maximum inconsistency for the data presented in this work is 10%. 相似文献
69.
70.